You talk about Apple Volume licensing, but how does that work for the "default" apps, I don't care if they're core or provided for free with the purchase of the system.. they're default apps.
The volume licensing for the core apps, the apps that are installed as part of OSX, are handled as the OS X license. These apps are only updated with the operating system, not individually. The iLife apps are the company's to do with as they wish. They are consumer apps for storing photos, making home movies and making home music. They don't even have to be left on a corp Mac. If the individual employee assigned the Mac has their own Apple ID, they can use that to install any of their personally acquired consumer apps of their choosing, apart from any software that the company has installed, as long as the Mac is solely in that employee's control.
I need to use a generic apple ID for my devices, and then provide that password to everyone in my company? Yeah. That's totally secure. Let me remind you that apple IDs have credit cards associated with them. Or I have to create new apple IDs for each device, tie those to the computer and provide that to my users? That's totally sustainable.
First, Apple IDs do not have to have credit cards associsted with them, especially if the company is making volume license purchases. I have never suggested that my clients go the generic Apple ID you posit here. My clients create Apple IDs for each Mac using email addresses created with their company domain. As long as an Apple ID does not use an Apple email domain, the email can be changed as needed, also the password.
Apple Volume Licensing -
http://www.apple.com/business/vpp/
Creating a new Apple ID for an iTunes Store, App Store, iBookstore, and Mac App Store account without a credit card -
http://support.apple.com/kb/HT2534
Changing the email address you use for your Apple ID -
http://support.apple.com/kb/HT5621
Manage your Apple ID -
https://appleid.apple.com/cgi-bin/WebObjects/MyAppleId.woa/